Heater



FIG. 1 is an isometric view depicting one embodiment of my new design;

FIG. 2 is a front elevational view depicting the embodiment of FIG. 1; and,

FIG. 3 is a right elevational view depicting the embodiment of FIG. 1.

The broken line showing is included for the purpose of illustrating portions of the article and forms no part of the claimed design. 

The ornamental design for a heater, as shown and described. 